Those '79 axles are the same year and axle combo (14 bolt/D44) that I've got in my truck now.
The only difference between full-time and part-time axles is the locking part of the hubs in the front axle. In the front axle of a full-time rig, you'll have a "permanent" hub...it's just a big gear. All you have to do is pop off the cover, remove a snapring, and then pull out that large gear. Toss it in your pile of parts because you won't need it anymore. Then, once things are rebuilt, just install some manual, internal locking hubs. You don't have to do anything special to install these.
As for the set of axles you got for free. Pop off the differential covers and post up the numbers you see on the ring-gear (they will be stamped somewhere on the outside of the ring-gear). Post the numbers you see for the front axle and the rear axle and someone here will tell you the gear ratios (and whether they match) and the year of the axles (provided the gear set they have now is what they came with from the factory).